System of distribution.



v PATENTED APR- 14, 1903. A.D.LUNT. SYSTEM OF DISTRIBUTION. vAPPLICATION FILED NOV. 30, 1900. RENEWED AUG. 4, 1902.

y no MODEL.

2 BHEETSSHEBT 1.

Witnesses.

No. 725,463. PATBNTED APR. 14, 1903.

AT D. LUNT.

SYSTEM OF DISTRIBUTION.

APPLICATION FILED NOV, so, 1900. RENEWED AUG. 4, 1902. I0 10mm. v 2SHEETS-SHEET 2 UNITED STATES PATENT OF ICE.

ALEXANDER D. LUNT, OF SCHENECTADY, NEWV JYORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEWYORK.

SYSTEM OF DISTRIBUTION.

SPECIFICATION forming part of Letters Patent No. 725,463, dated April14, 1903 Application filed November 30, 1900. Renewed August 4, 1902.Serial No. 118 ,359- (No model-) of dynamo-electric machines havingcollector-- rings connected to an alternatingcu rrent system and acommutator connectedto a directcurrent system.

One aim of my invention is to obtain a point of neutral potential on thealternatingcurrentsystem to which may be connected a conductorcooperatin g with the direct-current mains to produce amultiple-conductor distribution system. I

Another object of my invention is to reduce the amount of energy lost inthe heating of the armature-conductors of machines of the characterspecified. I

The invention is shown diagrammatically in the accompanying drawings andits fea tures of novelty pointed out'in the claims appended hereto.

Figure 1 shows the invention asapplied to a single-phase'system, Fig. 2being an explanatory diagram. Fig.3 shows the invention embodied in amultiphase system, Fig. 4 being a diagram explanatory of the same.

The invention is particularly useful in connection with single-phaserotary converters, although of course not limited thereto, and in Fig. 1of the drawings I have shown the application of the invention toa'machine of this character. At 1 is represented the armature-winding ofthe converter, to which in this case six equispaced taps 2, 3, 4, 5, 6,and 7 are connected, the outer ends of the taps being joined tocorresponding collector-rings, as shown.

A commutator 8 of ordinary construction is connected to the winding 1,the connections being omitted from the drawings for the sake ofclearness, these connections, however, being made in any manner wellknown in the art. Upon the commutator bear brushes 9 and 10, connectedto the mains 11 and 12 of a direct-current distribution system.

The'various collector-rings connected to the munication withan'alternating-current system, (represented in this case by thealternating-current mains 13 and 14,) the connections being made throughthe medium of a transformer, (indicated diagrammatically at 15.) Thistransformer is provided with a single winding 16, connected across thealternating-current mains 13 and 14, and three separateinductively-related windings 17, 18, and 19,connected through suitableconductors to the collector-rings joined to the armaturewinding 1.

The winding 17 is connected across points in the armature separated fromeach other by one-half the polar pitch, which in a twopole machine, asrepresented in the drawings, corresponds to a diameter. The companionwindings 18 and 19 are connected, respectively, across points in thearmaturewinding separated from each other by less than, one-half thepolar pitch, the location of the points of connection'of each windingbeing such; as to correspond to a chord parallel to the diameter acrosswhich'the winding 17 is connected. I

In Fig. 2 the circumscribing circle represents the, distribution ofpotential about the armature winding 1. The diameter 21 (drawn as a fullline) represents the electromotive force between two diametricallyopposite points in the winding, and therefore corresponds to theelectromotive force between the taps 2 and 5, connected to the winding,and also to that of the transformer-winding 17, the terminals of whichare electrically connected to those taps. The chords 22 and 23, parallelto the diameter 21, represent in relative magnitude and phase theelectromotive forces existing between the pairs of taps 6 7'and 3 4,respectively. The windings 18 and 19, which are connected, respectively,to the pairs of taps 6 7 and 3 4 just mentioned, should therefore, ifthey act as sources of electromotive force, be proportioned so as tohave a value, as related to the single winding 17, corresponding to theratio between the chord 22 and the diameter 21 in theelectromotive-force diagram, Fig. 2. As the taps 2 to 7, inclusive, areconnected to the winding IOU represented by the circle 20.

the winding 17, connected across diametricy at equally-spaced points,the geometrical relation between the chords 22 23 and the diameter 21,representing the electromotive forces between these taps, is such as tomake the electromotive force across the diameter equal to twice thatacross either of the chords. This spacing of the'taps has been chosen asa convenient one; but it is to be understood that considerable variationtherefrom can be made Without departing from my invention.

Owing to the fact that the diameter 21 in the electromotive forcediagram, Fig. 2, passes through the center of the circle 20 it followsthat the middle point of the diameter is of neutral potential withrespect to the electromotive forces acting in the armature-winding 1,the potential distribution of which is Inasmuch as ally opposite pointsin the armature winding 1, has an electromotive force which isrepresented in Fig. 2 by the diameter 2t, it follows that the middlepoint of this winding 17 is neutral in potential with respect to thearmature-winding 1. This middle point (represented at 24) is thereforeconnected to the neutral conductor 25, which'is brought forward andcooperates with the direct current mains 11 and 12 to form a threewiresystem, such as shown.

In explaining the operation of the system,

suppose the same to be operating to convert alternating current intodirect current. In this case single-phase current is conveyed into thearmature-winding 1,'along the diameter 2 5, and also between the taps 34 and 6 7, representing, respectively, the ends of chords parallel tothe said diameter. The supply of current from the companion windings 18and 19 on the transformer 15 serves to increase the capacity of theconverter, and to do this without increasing the heating to such an eX-tent as would be the case if all of the energy were passed into theconverter-winding solely through the diametrically displaced taps 2 and5.

Fig. 3 represents a somewhat more extended application of my invention,whereby a twelve-phase dynamo-electric machine may be inductivelyconnected to a quarter-phase alternating-current system. In making thisconnection I employ two transformers 26 and 27, of which the windings 28and 29 of the respective transformers are connected in any suitablemanner to a quarter-phase alternating-current system. The other memberof each of the transformers comprises three separate windings, thewindings of the transformer 26 being designated by the letters a Z) 0,while those on the transformer 27 are similarly designated by theletters d cf.

Fig. 3 shows the transformer-windings as connected across points in arotary converterarmature 28, the manner of making the connections beingperhaps more clearly indicated in the diagram in Fig.4. The winding a ofone of the phases is connected across a chord two adjacent poles.

of the armaturewinding represented diagrammatically by the chordlettered Ct in Fig. 4. The winding b of the same phase is connectedacross a diameter as indicated by the diameter lettered I), while theremaining winding 0 is connected across the chord indicated at c in Fig.4, these chords and the diameter being parallel to each other, since theelectromotive forces in the windings are of the same phase.

The windings (1 cf of the transformer connected to the other phase ofthe quarterphase system constitutes seats of induced electromotiveforces displaced by a quarterphase from those induced in the windings a,b, and 0. These windings d, e, and fare connected in a similar manneracross points in the armature of the converter represented by the set ofparallel chordsfd and the diameter 6 parallel thereto, thelast-mentioned set of chords and the associated diameter being at rightangles'to the corresponding chords and diameter a, b, 0, respectively,this angular displacement representing the angular displacement betweenthe phases of the electromotive forces of the respective windings in thetransformers 26 27.

The points of connection between the transformer-windingsand theconverter-armature 31 being equally spaced constitute a twelvephaseconnection by means'of which energy may be conveyed between thedirect-current mains 30 of the converter and the alternatingcurrentmains 31 32 of the quarter-phase sys tem.

It is to be understood that the respective transformer-windingsconnected across diameters as represented at b and e in Fig. 4 are woundso as to have a slightly-larger induced the ratio between any one of thediameters.

and any one of the chords in Fig. 4. If the invention be applied tomachines of multipolar construction, as is usual in practice, it is ofcourse to be understood that while I have heretofore spoken of diametersthe same would in the case of a in ultipolar construction be representedby a connection of the armature-winding displaced by a distance equal tothe distance between the center of The. modifications required bychanges in the number of poles are, however, quite well understood byone skilled in the art, so that no further explanation is necessary. Aneutral conductor may be obtained in th construction in Fig. 3 byconnecting together the middle points of the windings b e and extendinga conductor therefrom, which conductor may so operate with thedirect-current mains 30 to produce a three-wire system. This neutralconductor is indicated at g and is connected to the middle points of thewindings b and e. The connection between these 7 ametersb e in Fig. 4,representing the electromotive forces of the correspondingly-designatedwindings.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

l. A rotary converter, means for feeding current of a given phase intothe armaturewinding acrosspoints separated by half the polar pitch, andmeans for feeding current of the same phase into the winding acrosspoints separated by less than half the polar pitch.

2. A dynamo-electric machine and an alternating-current system connectedthereto through a plurality of circuits of the same phase, one of whichis connected across points in the armature-winding of said machineseparated from each other by one-half the polar pitch and anotherconnected across points in the armature-winding separated by less thanhalf the polar pitch.

3. A dynamo-electric machine, and an alternating-current systemconnected thereto through a plurality of circuits of the same phase, oneof which is connected across points in the armature-winding of saidmachine separated from each other by an angle difierent from the angulardisplacement of the points of connection of another of said circuits.

4. The combination of a plurality of sources of alternating current ofthe same phase of connected thereto, a plurality of inductivelyrelatedtransformer-windings of unequal voltage, and connections between eachtransformer-winding and a pair of saidcollectorrings.

7. The combination of a plurality of alternating-current circuits, adynamo-electric machine, and connections between said circuits and awinding of said machine such that the electromotive force between thepoints of connection of one of the circuits is of the same phase as butdifferent value from that between the points of connection of another ofsaid circuits. 7

8. The combination of an alternating-current system including aplurality of circuits, at dynamo-electric machine, connectionsbetweensaid circuits and a winding of said machine such that the electromotiveforce betweenthe points of connection of one of the circuits is of thesame phase as but different in value from that between the points ofconnection of another of said circuits, a directcurrent'system connectedto said dynamoelectric machine, and a neutral conductor cooperating withsaid direct-current system and connected to a point on thealternatingcurrent system.

9. The combination of an alternating-current system including aplurality of circuits, a dynamo-electric machine, connections betweensaid circuits and a winding of said machine such that the electromotiveforce between the points of connection of one of the circuits is of thesame phase as but diflferent in value from that between the points ofconnection of another of said circuits, a directcurrent system connectedto said dynamoelectric machine, and a neutral conductor-cooperating withsaid direct-current system and connected to'a point of neutral potentialon the alternating-current system.

10. The combination of a dynamo-electric machine, a plurality of sets ofmultiphase windings, and connections'between each set of windings of thesame phase and a winding 1 of said machine such that terminals of likepolarity of each set are connected to separate but adjacent points inthe winding of said machine.

11. The combination of a dynamo-electric machine, a plurality of sets ofmultiphase windings, connections between each set of windings of thesame phase and a winding of said machine such that terminals oflikepolarity of each set are connected to separate but adjacent pointsin the winding of said

